Assignment: Digital I/O with Arduino Boards + Diffuser

Collaborators:

Assignment: Digital I/O with Arduino Boards + Diffuser
Collaborators:

Assignment: Digital I/O with Arduino Boards + Diffuser

Description: In this lab, we used the Serial Communication feature of the Arduino board to control the Pulse Width Modulation of three LEDs.  We connected 3 LEDs to the Arduino board at the PWM locations (pins 9, 10, 11).  With this functioning, I experimented with diffusers of different shapes made from tissue paper and printer paper.

Materials Used:

• Arduino board
• 3 220 ohm resistors
• 3 LEDs
• wire
• breadboard
• usb cable
• computer
• paper (printer, tissue)

Code:

/* 
 * Serial RGB LED
 * ---------------
 * Serial commands control the brightness of R,G,B LEDs 
 *
 * Command structure is "<colorCode><colorVal>", where "colorCode" is
 * one of "r","g",or "b" and "colorVal" is a number 0 to 255.
 * E.g. "r0"   turns the red LED off.  
 *      "g127" turns the green LED to half brightness
 *      "b64"  turns the blue LED to 1/4 brightness
 *
 * Alternate command structure is "<colorCode>*", where "colorCode" is
 * one of "r","g", or "b".
 * E.g. "r"    increases the red LED brightness by 10
 *      "rrr"  increases the red LED brightness by 30
 *      "ggb"  increases the green LED brightness by 20 and the blue by 10
 *
 * Created 18 October 2006
 * copyleft 2006 Tod E. Kurt <tod@todbot.com
 * http://todbot.com/
 *
 * Adapted 5 September 2007
 * copylefter 2007 Ryan Aipperspach <ryanaip@alumni.rice.edu>
 *
 */
 
//include support for manipulating strings.
//for a useful string comparison function, see the bottom of this file... stringsEqual()
//#include <stdio.h>
#include <string.h>

char serInString[100];  // array that will hold the different bytes of the string. 100=100characters;
                        // -> you must state how long the array will be else it won't work properly
char colorCode;
int colorVal;

int redPin   = 9;   // Red LED,   connected to digital pin 9
int greenPin = 10;  // Green LED, connected to digital pin 10
int bluePin  = 11;  // Blue LED,  connected to digital pin 11

int redValue = 127;
int greenValue = 127;
int blueValue = 127;

void setup() {
  pinMode(redPin,   OUTPUT);   // sets the pins as output
  pinMode(greenPin, OUTPUT);   
  pinMode(bluePin,  OUTPUT);
  Serial.begin(9600);
  analogWrite(redPin,   redValue);   // set them all to mid brightness
  analogWrite(greenPin, greenValue);   // set them all to mid brightness
  analogWrite(bluePin,  blueValue);   // set them all to mid brightness
  Serial.println("enter color command (e.g. 'r43 or rrrrrrrrbbbb') :");  
}

void loop () {
  //read the serial port and create a string out of what you read
  readSerialString(serInString, 100);

  
    
  //UNCOMMENT ONE OF THE FOLLOWING COMMANDS, OR NOTHING WILL HAPPEN WHEN YOU
  //RUN THE PROGRAM...
  
  //Uncomment the following line to read commands of the form 'r245' or 'b3'  
  //processNumericalCommands(serInString);
  
  //Uncomment the following line to read commands of the form 'rrrb'
  processRepeatKeyCommands(serInString, 100);
  
  //Or write your own function...
  //YOUR_FUNCTION_HERE(serInString);



  //Erase anything left in the serial string, preparing it for the 
  //next loop
  resetSerialString(serInString, 100);  

  delay(100);  // wait a bit, for serial data
}

void resetSerialString (char *strArray, int length) {
  for (int i = 0; i < length; i++) {
    strArray[i] = '\0';
  }
}

//read a string from the serial and store it in an array
//you must supply the array variable
void readSerialString (char *strArray, int maxLength) {
  int i = 0;

  if(!Serial.available()) {
    return;
  }
  while (Serial.available() && i < maxLength) {
    strArray[i] = Serial.read();
    i++;
  }
}

//go through the string, and increase the red value for each 'r',
//the green value for each 'g', and the blue value for each 'b'.
//For example "rrrg" increases red by 30 and green by 10.
void processRepeatKeyCommands(char *strArray, int maxLength) {
  int i = 0;
  
  //loop through the string (strArray)
  //i = the current position in the string
  //Stop when either (a) i reaches the end of the string or
  //                 (b) there is an empty character '\0' in the string
  while (i < maxLength && strArray[i] != '\0') {
    //Read in the character at position i in the string
    colorCode = serInString[i];
    
    //If the character is r (red)...
    if (colorCode == 'r') {
      //Increase the current red value by 10, and if you reach 255 go back to 0
      redValue = (redValue + 10) % 255;
      analogWrite(redPin, redValue);
      Serial.print("setting color r to ");
      Serial.println(redValue);
      
    //If the character is g (green)...
    } else if (colorCode == 'g') {
      greenValue = (greenValue + 10) % 255;
      analogWrite(greenPin, greenValue);
      Serial.print("setting color g to ");
      Serial.println(greenValue);
    
    //If the character is b (blue)...
    } else if (colorCode == 'b') {
      blueValue = (blueValue + 10) % 255;
      analogWrite(bluePin, blueValue);
      Serial.print("setting color b to ");
      Serial.println(blueValue);
    }
    
    //Move on to the next character in the string
    //From here, the code continues executing from the "while" line above...
    i++;
  }
}

//change the value of the red, green, or blue LED according to the command received.
//for example, r240 sets the red LED to the value 240 (out of 255)
void processNumericalCommands(char *strArray) {
  //read in the first character in the string
  colorCode = serInString[0];
  
  //if the first character is r (red), g (green) or b (blue), do the following...
  if( colorCode == 'r' || colorCode == 'g' || colorCode == 'b' ) {
    //convert the string to an integer
    //(start at the second character, or the beginning of the string '+1')
    colorVal = atoi(serInString+1);
    Serial.print("setting color ");
    Serial.print(colorCode);
    Serial.print(" to ");
    Serial.print(colorVal);
    Serial.println();

    if(colorCode == 'r') 
      analogWrite(redPin, colorVal);
    else if(colorCode == 'g')
      analogWrite(greenPin, colorVal);
    else if(colorCode == 'b')
      analogWrite(bluePin, colorVal);
  }
}

//compare two strings to see if they are equal
//compares the first 'numCharacters' characters of string1 and string2 to
//see if they are the same
//
//E.g. stringsEqual("hello","hello",5) => true
//     stringsEqual("hello","helaabbnn",3) => true
//     stringsEqual("hello","helaa",5) => false
boolean stringsEqual(char *string1, char *string2, int numCharacters) {
  if (strncmp(string1, string2, numCharacters) == 0) {
    return true;
  } else {
    return false;
  }
}

Arduino with 3 LEDs connected to the PWM pins.

Same set-up with paper column diffuser.

Fanlike diffuser made of two pieces of paper.

Irregularly shaped diffuser made of tissue paper.